Thread by @ejustin46

𝙃5𝙉1 𝘼𝙑𝙄𝘼𝙉 𝙄𝙉𝙁𝙇𝙐𝙀𝙉𝙕𝘼 :
𝙃𝙤𝙬 𝙃5𝙉1 𝙞𝙨 𝙏𝙍𝘼𝙉𝙎𝙈𝙄𝙏𝙏𝙀𝘿 ?
𝙒𝙝𝙖𝙩 𝙖𝙧𝙚 𝙩𝙝𝙚 𝙍𝙄𝙎𝙆 𝙛𝙤𝙧 𝙃𝙐𝙈𝘼𝙉𝙎 ?
(2𝘯𝘥 𝘱𝘢𝘳𝘵)
▶️ Underestimation of cases
▶️ Overestimation of fatality rate

2) 𝙐𝙣𝙙𝙚𝙧𝙚𝙨𝙩𝙞𝙢𝙖𝙩𝙞𝙤𝙣 𝙤𝙛 𝙘𝙖𝙨𝙚𝙨 :
"We are underestimating, again, the true burden of H5N1 in humans"


Clade 2.3.4.4b H5N1 avian influenza viruses have spread globally since 2020, causing major outbreaks in poultry and ...ncbi.nlm.nih.gov/pmc/articles/P…

3) ...infecting a wide range of mammal species.
The true number of human H5N1 infections from this strain is unknown but likely significantly underestimated, especially as the viruses can infect mammals. Only 12 cases have been reported to WHO since 2020.

4) A study conducted by the authors in 5 live bird markets in Egypt found a 4.6% seroprevalence of antibodies to clade 2.3.4.4b H5N1 in market workers. This suggests more widespread subclinical human infection than reported cases.

5) Seropositivity correlated with detection of the virus in birds sold at the markets, indicating the markets are a source of human exposure. Some workers seroconverted over the study period.
The 4.6% seroprevalence is much higher than estimates from previous H5N1 strains ...

6) ...in Egypt, suggesting clade 2.3.4.4b infects mammals more efficiently.
Surveillance data underestimates true infection rates. Estimates of thousands of asymptomatic infections globally are plausible based on the Egyptian data.

7) 𝙊𝙫𝙚𝙧𝙚𝙨𝙩𝙞𝙢𝙖𝙩𝙞𝙤𝙣 𝙤𝙛 𝙛𝙖𝙩𝙖𝙡𝙞𝙩𝙮 𝙧𝙖𝙩𝙚
"Debate on H5N1 death rate and missed cases continues"


There is an ongoing debate about the true case fatality rate (CFR) of H5N1 avian influenza in humans. The WHO estimates it is ...cidrap.umn.edu/avian-influenz…

8) ...around 59% based on reported cases, but some argue this excludes many milder/asymptomatic infections.
Palese's group analyzed multiple studies and estimated a 1-2% overall seroprevalence rate, suggesting millions of missed infections globally and a lower true CFR.

9) Osterholm's group focused on studies meeting WHO criteria and found a lower 0.47% rate. They argue current CFR estimates are reasonable and a pandemic would still be catastrophic even with a lower rate.

10) There is disagreement about how to weigh and compare heterogeneous serostudies. Most experts believe H5N1 still poses a serious pandemic risk even if the true CFR is somewhat lower.

11) So in summary, while the debate continues, most researchers think H5N1 remains a severe threat, although the true CFR may be somewhat lower than WHO estimates based on more limited evidence of some subclinical cases.

Thanks for reading 🙏